Viability of Starter Bacteria and Anti-Oxidative Activity of a Functional Yogurt Containing Silybum marianum Seed Extract

Silybum marianum seed extract (silymarin) is rich in phenolic compounds with anti-oxidative activity that add beneficial and healthful properties to silymarin-enriched products. The present study investigated effects of silymarin on characteristics of a functional yogurt. 

In this study, yogurt was enriched with Silybum marianum seed extract at concentrations of 0, 25, 50 and 100 mg l-1 milk and the samples were analyzed for physicochemical and sensory properties and viability of starter bacteria during 21 days at 4°C at 7-day intervals. 

Results showed that increasing silymarin proportion in yogurt samples increased anti-oxidative activity, total phenolic content, total viability of Lactobacillus delbrueckii and decreased pH value, viscosity and sensory attributes (p<0.05). Furthermore, pH, viscosity, anti-oxidative activity, phenolic compounds and sensory attributes decreased during storage (P<0.05). In conclusion, 25 mg Silybum marianum seed extract per one liter of milk can be used for the preparation of yogurts with healthy properties.